1. Activate SSI on Tomcat and restart Tomcat
2. create an any html-file with a comment like this "<!--#-->"
3. put this html-file to the webapp folder of tomcat
4. when you now go to the html file via tomcat, you will get an Nullpointer Exception. The SSIServlet.class and other necessary SSI-classes cannot be found

Proposed for 6.0.
For the record:
1. The stacktraces in 6.0 are, for SSIServlet and SSIFilter:
java.lang.NullPointerException
org.apache.catalina.ssi.SSIProcessor.process(SSIProcessor.java:132)
org.apache.catalina.ssi.SSIServlet.processSSI(SSIServlet.java:208)
org.apache.catalina.ssi.SSIServlet.requestHandler(SSIServlet.java:174)
org.apache.catalina.ssi.SSIServlet.doGet(SSIServlet.java:110)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
java.lang.NullPointerException
org.apache.catalina.ssi.SSIProcessor.process(SSIProcessor.java:132)
org.apache.catalina.ssi.SSIFilter.doFilter(SSIFilter.java:142)
2. With the patch applied, processing the "<!--#-->" comment replaces it with the following text:
"[an error occurred while processing this directive]"
and the following is logged into localhost.*.log file:
org.apache.catalina.core.ApplicationContext log
INFO: Unknown command:
This is OK, because there is very little difference between an empty command name and a wrong command name. If one treats it as a comment and writes any random text after the '#', it would trigger the same error message.

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